Five Pleurotus pulmonarius strains obtained by interbreeding of monokaryotic mycelia isolated from a commercial strain were studied. The aim was to identify germplasm adequate to industrial production. Pasteurized barley straw was used as the substrate for mushroom production. Two treatments were tested: barley straw fermented during 7 days (PCF) and unfermented straw (PC). The mean biological efficiency of the strains was 55.73% (PCP) and 71.25% (PC), while the production rate was 0.64% (PCF) and 0.92% (PC), after four flushes, with a mean production period of 66 days (PCF) and 58 days (PC). During fermentation period, the straw showed a maximum temperature (64°C) at five day. Prior to sowing, the pH of PCF was 9.4 with 74% moisture and control (PC) had a pH of 8.5 and 73% moisture. During the fermentation the initial C:N in the control was 76% (dry basis) and in the PCF decreased gradually until 47% at seven day. Some of the strains generated increased their productivity. However, their efficient use will depend on the substrate conditions on which the strain grow.